枇杷Ty1-copia类反转录转座子RT序列克隆及分析

Cloning and Sequence Analysis of the Ty1-copia Retrotransposon Reverse Transcriptase Gene from Eriobotrya japonica

为探索枇杷Eriobotrya japonica基因组进化起源和多样性的关系,本文根据Tyl-copia类反转座子反转录酶(Reverse transcriptase,RT)的保守区设计简并引物,通过PCR扩增,经过克隆、测序及序列分析,获得了59条来源于枇杷的RT序列。通过系统演化分析,所得核苷酸序列可分为4个群组,序列长度变化范围为241~282 bp,同源性范围为30.8%~100%;编码氨基酸中有17条序列出现终止密码子突变;经反转录转座子RT氨基酸序列比对,枇杷与苹果、李、梅等蔷薇科植物亲缘关系较近。因此,枇杷Ty1-copia类反转录转座子RT序列具有高度异质性,枇杷与蔷薇科物种间有共同起源,而且Ty1-copia类反转座子不仅可以纵向传递,还可在不同类群间横向传递。

Retrotransposon widely exists in eukaryotic organisms,and is a class of mobile genetic factors,and highly contributes to plant genome size and structure,gene function,as well as gene and genome evolution.In order to elucidate the relationship between the evolutionary origin and diversity of Eriobotrya japonica genome,the target fragments were amplified by PCR using the degenerate primers designed according to the conserved domain of Ty1-copia reverse transcriptase.The amplified products were cloned and sequenced.Totally,59 sequences of reverse transcriptase were obtained from Eriobotrya japonica.The phylogenetic analysis suggested that they could be divided into 4 groups.The nucleotide sequences demonstrated high heterogeneity,and sequence length varied from 241 bp to 282 bp with homology ranging from 30.8%to 100%.In coding region,stop codon mutation presented in 17 sequences.Amino acid sequence of Eriobotrya japonica showed highly homologous with Rosaceae species,e.g.Malus domestica,Prunus salicina and Prunus mume.Therefore,the Ty1-copia retrotransposons of Eriobotrya japonica and other rosaceous plants may share the same origin,and the Ty1-copia retrotransposons can not only longitudinally transmit,but also transversely transfer among the different groups.